1. Field of the Invention
The present invention relates to a speech recognition system capable of recognizing utterances and method for speech recognition.
2. Description of the Related Art
Recently, for example, cases have become common where, when inquiries, complaints, consultation requests, and the like about purchased products from users are accepted by telephone, a call center to which operators who answer telephone calls from users are assigned is established. A suitable number of operators are assigned to a call center so as to quickly answer telephone calls from users.
In general, in such a call center, dialogs between operators and users are recognized using a speech recognition system to record the dialogs as the result of recognition. Recorded dialogs may be displayed on the display screen of a personal computer for an operator. When dialogs between operators and users are recorded, for example, what information users like to know can be analyzed. The result of analysis can be utilized as, for example, hints for future business operation. Moreover, the result of analysis can be utilized for operators' smooth operations by incorporating the result of analysis in manuals held by operators.
In a speech recognition system, when a dialog between an operator and a user is erroneously recognized, the content of the dialog is recorded on the basis of the result of erroneous recognition. When the content of the dialog is recorded on the basis of the result of erroneous recognition, accurate analysis cannot be performed. Thus, the erroneous recognition by the speech recognition system needs to be corrected. For example, Japanese Unexamined Patent Application Publication No. 11-149294 and Japanese Unexamined Patent Application Publication No. 2005-123869 described below are known as methods for correcting erroneous recognition by a speech recognition system.
In Japanese Unexamined Patent Application Publication No. 11-149294, there is disclosed a method for, when a speech recognition system erroneously recognizes a user's utterance, correcting the erroneous recognition by the speech recognition system by a user's reutterance (restatement). Specifically, when a restatement determination unit determines that a user's reutterance is an utterance for restatement, a recognition processing unit outputs an adjusted recognition candidate using both past recognition candidates stored in a recognition candidate registration unit and a recognition candidate obtained in the current processing. Thus, when the user can recognize the erroneous recognition, the erroneous recognition can be corrected by an utterance for restatement.
Moreover, in Japanese Unexamined Patent Application Publication No. 2005-123869, there is disclosed a call content transcription system that facilitates confirmation and correction of the result of recognition by separating the content of a call that is sent and received via telephone handsets to a part of a caller and a part of a callee. Specifically, speech from a channel on a caller's side is recognized by first speech recognition means, and speech from a channel on a callee's side is recognized by second speech recognition means. Speech recognized by the first speech recognition means and the second speech recognition means is converted to character strings by character string conversion means to be displayed on display means. The character strings displayed by the display means are edited using input means, for example, a keyboard. Thus, since the content of a call by a caller and a callee is displayed in chronological order, an editor can readily transcript the content of the call.
In a call center, the result of recognizing a dialog between an operator and a user can be displayed on the display screen of a personal computer for the operator. Thus, the operator can check whether the result of recognition is correct. In contrast, the user cannot check the result of recognition. That is to say, in many cases, a user is not conscious that a dialog between an operator and the user is recognized by a speech recognition system, and the dialog, which is the result of recognition, is recorded. Thus, even when a speech recognition system has erroneously recognized a dialog between an operator and a user, the user keeps uttering without an utterance for restatement. Accordingly, the method for correcting erroneous recognition disclosed in Japanese Unexamined Patent Application Publication No. 11-149294 cannot be applied to such a case.
On the other hand, when a speech recognition system has erroneously recognized a dialog between an operator and a user, the operator needs to correct the result of erroneous recognition. Specifically, the operator corrects the result of erroneous recognition displayed on the display screen of a personal computer by operating a keyboard. However, it is difficult to correct the result of erroneous recognition by operating a keyboard without interrupting the dialog between the operator and the user. Thus, the result of erroneous recognition may be corrected by operating a keyboard after the dialog between the operator and the user is completed. However, in this case, the operator needs to remember a place where the result of erroneous recognition has occurred, a result of correct recognition, and the like. Moreover, when the dialog between the operator and the user is recorded, the operator need not remember a place where the result of erroneous recognition has occurred, a result of correct recognition, and the like. However, it takes much time and effort to hear the recorded dialog again. Thus, the method for correcting erroneous recognition disclosed in Japanese Unexamined Patent Application Publication No. 2005-123869 cannot be applied to such a case.